SNiP-TDR for Soil Moisture
The SNiP-TDR is a 'Sensor Node Integrated Package' for LoRaWAN or CAT-M1 communication of real-time soil moisture measurements for continuous soil monitoring.
SNiP-TDR
The SNiP-TDR integrates 1x S-NODE and 1x TDR-315L to a site’s unique network, communication and power requirements.
The TDR-315L provides a measurement of Volumetric Soil Water % (VSW), based on the Time Domain Reflectometry (TDR) measurement principle.
See Further Specifications on the S-NODE
See Further Specifications on the TDR-315L Sensor
Extended SNiP-TDR
Further parameters can be added to SNiP-TDR, without requiring loggers to match each distinct sensor, substantially reducing the cost of getting a fuller picture on the application. The S-NODE can support an added 3x TDR-315L sensors or 3x other SDI-12 sensors to monitor soil moisture at multiple depths. Extensions include sensors that measure:
- other soil parameters (such as the TEROS-21)
- plant monitoring parameters (such as the DPS40 Pivot Stem Dendrometer, DBS60 Dendrometer)
- environmental parameters (such as the ATMOS-14, SP-421 Pyronometer)
The TDR-315L is a true Time Domain Reflectometer system (minus the coaxial cable) wrapped up in a small, rugged, permanently installable package. This model uses half the power yet it sacrifices none of the accuracy of its big brother the TDR-315. Acclima True TDR technology is a major, patented breakthrough in soil water and EC measurement technology.
- Volumetric Water Content (0 to 100% with 0.1% resolution)
- Permittivity (1 to 80 with 0.1 unit resolution)
- Soil Electrical Conductivity a.k.a. Bulk EC (0 to 5000 μS/cm -resolution depends on reading range)
- Soil Temperature (-40 to +60°C with 0.1 degree resolution)
- Pore Water Electrical Conductivity (0 to 55000 μS/cm)
Features:
- 10 meter, flexible, waterproof cable
- 15 cm X 3.5mm stainless steel 3-element waveguide
- Rugged, waterproof epoxy housing
- Typical 350ps incident wave rise time applied directly to the soil (no bandwidth limiting coax cable).
- Input bandwidth to the waveform digitiser is also unrestrained because of the absence of a coax cable.
S-NODE
The S-NODE (for Environmental Monitoring) has been designed to support the broad suite of SDI-12 based environmental sensors. The S-NODE can support sensors with higher power requirements; a solar panel can charge either the internal lithium-ion battery or both the node and sensor can be powered by an external 12V system (e.g. battery or mains source).
A decoder suitable for TTN will be provided based upon sensor configuration.
- LoRaWAN™ low-power long-range connectivity
- Supports the full range of SDI-12 commands and sensors requiring constant excitation.
- Optional CAT-M1
- Solar rechargeable Lithium-ion or external 12V power options
- Optional Multi-constellation GNSS
- AS923, AU915, US915, EU868 and CN470 available, with other region plans available upon request.
- Standard IP65 enclosure, optional IP67
TDR-315L
The TDR-315L is a true Time Domain Reflectometer system (minus the coaxial cable) wrapped up in a small, rugged, permanently installable package. This model uses half the power yet it sacrifices none of the accuracy of its big brother the TDR-315. Acclima True TDR technology is a major, patented breakthrough in soil water and EC measurement technology.
- Volumetric Water Content (0 to 100% with 0.1% resolution)
- Permittivity (1 to 80 with 0.1 unit resolution)
- Soil Electrical Conductivity a.k.a. Bulk EC (0 to 5000 μS/cm -resolution depends on reading range)
- Soil Temperature (-40 to +60°C with 0.1 degree resolution)
- Pore Water Electrical Conductivity (0 to 55000 μS/cm)
| Operating Parameters: | |
| Read time: | 0.7 seconds |
| Voltage Requirements: | 6 to 15 volts DC |
| Idle Current Consumption: | < 30 μA @ 6 to 15 VDC |
| Read Current Consumption: | 170 mA @ 6 to 15 VDC |
| Idle Energy Consumption: | 15 J per day at 6 VDC |
| Read Energy Consumption: | 0.7 J per reading at 6 VDC, 1.4 J per reading @ 12 VDC |
| VWC and Permittivity Performance Specifications | |
| Permittivity to VWC conversion method: | Proprietary Dielectric Mixing Model with 0 to 100% range. Closely follows Topp Equation to 46% VWC. |
| Permittivity Reporting Accuracy: | ±1% of full scale 1 to 80 relative permittivity units From 0 to 4000 μS/cm Bulk (in-soil) Electrical Conductivity From –20°C to +50°C. The VWC reading will only report liquid water. |
| VWC Accuracy: | Dependent upon soil type – but typically ±2% <1% change with Bulk EC changes from 0 to 4000 μS/cm Change in VWC with compaction follows only the change in soil volume. |
| Temperature: | Precision thermistor located within 2 mm of the outer waveguide rod where it enters the epoxy housing. |
| Accuracy: | Typical ±0.2°C, Worst Case ±0.5°C over -12 to +50°C |
| Electrical Conductivity: | Calculated from long term (200 ns) amplitude of reflected wave using the ‘waveguide constant’. Derived in factory during calibration. |
| EC Accuracy: | ±1%, ±35 μS/cm maximum error from 0 to 5000 μS/cm Bulk EC*. |
*Note that the 1% error applies to higher values of EC while the 35 μS/cm error applies to very low values of EC.
Pore water EC is calculated from the Hilhorst model using an average pore size to represent all soils. Hence its accuracy is not specified. The reading does provide a ‘ballpark’ indication of the salinity of the water in the soil as opposed to the soil/water mixture or ‘Bulk EC’ property.